Two time-scale model based adaptive control for helicopter under unknown wind conditions

Two time-scale model based adaptive control method is proposed for a helicopter to overcome wind disturbances in this paper. Wind disturbances are considered as a mixture of four sinusoidal signals with unknown frequencies, amplitudes and phases. The controller is designed based on the concept of time-scale separation, which has the advantage of decoupling of the rotational and translational dynamics. Backstepping control and inverse dynamic control method are used to design the fast controller and the slow controller individually and different control intervals are used for the two models. Unscented Kalman filter (UKF) is used for online estimation of wind disturbances. The results from UKF are used for the adaptive reconfiguration of the two time-scaled model based controller. Simulation results show that the adaptive control method reduces the impact of wind disturbances and achieves good performance.